Among a variety of secondary batteries currently present, a bipolar-type lithium ion secondary battery (hereinafter, also described as a bipolar battery) excellent in energy density and output density have attracted attention. As disclosed in Japanese Extent Laid-Open Publication No. 2000-100471, a bipolar battery has a structure composed in such a manner that bipolar electrodes, each of which is composed by stacking a positive electrode active material layer, a current collector and a negative electrode active material layer in this order, and separators are stacked alternately.
The respective constituents of the bipolar battery for use in a mobile body such as a vehicle have been designed so that a thickness of each separator can be extremely thin as compared with a thickness of each positive electrode active material layer and a thickness of each negative electrode active material layer. This has been because a capacity and output of the bipolar battery are attempted to be increased by maximizing ratios occupied by the positive electrode active material layers and the negative electrode active material layers in a limited thickness of the bipolar battery itself.
However, since heat generation amounts of the positive electrode active material layers and the negative electrode active material layers are large, there has been a problem that heat becomes prone to accumulate in an inside of the battery by the fact that the ratios of these electrode active material layers are increased, thus making it prone to cause deteriorations of the electrolyte and the like, which are contained in the battery. This has been one of causes to decrease the output and service life of the battery.
Moreover, there is a problem that the conventional bipolar battery is prone to be affected by vibrations in terms of a structure thereof, resulting in that the respective layers composing the bipolar battery became prone to be dissociated from one another by the vibrations. This has also been one of the causes to decrease the output and service life of the battery.